1. Field of the Invention
The present invention relates to a mechanism for exhausting waste developing powder from a developing unit provided in an image forming apparatus of an electronic photography type.
2. Description of the Related Art
In the image forming apparatus of an electronic photography type, when the number of processed copies reaches several thousands to several hundred thousands, the life of developing powder is expired. This results in degrading the quality of a copied image and bringing about the splash of developing powder to the inside of the main body of the image forming apparatus.
To smoothly remove the waste developing powder, the inventors of the present application know there has been proposed a mechanism for exhausting waste developing powder. In the known mechanism, there is provided a screw for exhausting developing powder. When exhausting the waste developing powder, the exhausting screw is driven to convey the developing powder toward an exhaust outlet.
If the developing unit is left untouched for a long time, it is likely that the developing powder may become solid due to the influence of the circumstance around the powder. The solid developing powder has an inferior fluidity.
However, the known mechanism is not capable of efficiently exhausting the solid developing powder. That is, the exhausting screw does not enable to smoothly move the solid developing powder. This results in consuming a long time until the termination of exhausting the waste developing powder. This long time is wasteful, because no work can be done for the image forming apparatus during the time.